1. Field of the Invention
The present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition which is suitably used in an ultramicrolithographic process which is applicable to a production process such as a production process of ultra-large scale integrations (LSIs) and high capacity microchips, a manufacturing process of a nanoimprint mold, and a production process of a high density information recording medium, and other photofabrication processes, as well as an actinic ray-sensitive or radiation-sensitive film, a mask blank provided with the actinic ray-sensitive or radiation-sensitive film, a pattern forming method, a method for manufacturing an electronic device, an electronic device, and a novel compound. More particularly, the present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition which can be suitably used for microfabrication of a semiconductor device using an electron beam, X-rays, or EUV light, as well as an actinic ray-sensitive or radiation-sensitive film, a mask blank provided with the actinic ray-sensitive or radiation-sensitive film, a pattern forming method, a method for manufacturing an electronic device, an electronic device, and a novel compound.
2. Description of the Related Art
In microfabrication using a resist composition, formation of an ultrafine pattern is required due to an increase in the integration degree of an integrated circuit. Accordingly, there is an additional tendency that the exposure wavelength becomes shorter, such as from g line to i line, or further to KrF laser light or ArF laser light. Further, lithography using an electron beam, X-rays, or EUV light instead of excimer laser light has recently been under development.
However, from the viewpoint of overall performance of a resist, it remains very difficult to find a suitable combination of a resin, a photoacid generator, a basic compound, an additive, a solvent, and the like to be used. In particular, upon considering recent demand for the formation of an ultrafine pattern (for example, one having a line width of 50 nm or less) with high performance, it cannot be yet said that currently available lithography is sufficient in terms of its performance.
Typically, even in the case of providing an unexposed area intended to be removed by a developer and an exposed area not intended to be removed by a developer on a resist film when performing exposure, a region within the unexposed area being adjacent to the exposed area is subjected to exposure even in a low exposure dose (hereinafter, this region is referred to as “weakly exposed area”). Therefore, even a weakly exposed area becomes insoluble or poorly-soluble in connection with a developer, which, in turn, leads to occurrence of scum and bridging between patterns formed by the development.
In the field of an electron beam (EB) lithography, it has been found that the influence of electron scattering in a resist film (that is, forward scattering) is reduced by increasing the acceleration voltage of an EB. Accordingly, there has been recently a tendency to increase the acceleration voltage of an EB. However, if the acceleration voltage of an EB is increased, the influence of forward scattering is reduced, whereas the influence of scattering of electrons reflected in a resist substrate (that is, backward scattering) is increased. In addition, in the case of forming an isolated space pattern having a large exposure area, the influence of backward scattering is particularly significant. Thus, for example, an increase in the acceleration voltage of an EB may possibly result in occurrence of scum and bridging between isolated space patterns.
Particularly, in the case of patterning on a photomask blank used for semiconductor exposure, since a light-shielding film containing heavy atoms such as chromium, molybdenum, and tantalum is present as a layer below a resist film, the influence of backward scattering due to reflection from a layer below a resist film is more significant in comparison to the case of applying a resist onto a silicon wafer. As a consequence, in the case of forming an isolated space pattern on a photomask blank, the pattern is particularly susceptible to the influence of backward scattering, and the resolution thereof is highly likely to decrease. On the other hand, in extreme ultraviolet (EUV) lithography, there is a possibility of generating scum and bridging between patterns, due to the flare light generated by the surface topology and a phase difference of a reflection mirror constituting an optical system of an exposure apparatus, and the unintended light of different wavelengths (Out of Band light: OoB light) from that of EUV light, which is generated due to the reflection mirror also exhibiting a certain degree of reflection characteristics with respect to wavelengths different from an exposure wavelength of EUV light (typically 13.5 nm).
Further, microfabrication using a resist composition is not only used directly in the production of integrated circuits but has also been recently applied to the fabrication or the like of a so-called imprint mold structure (see, for example, JP2002-148806A, JP2008-268935A, JP2002-6500A, and SPIE Vol. 1672 (1992) 157). To this end, in particular, even in a case of forming an ultrafine pattern (for example, one having a line width of 50 nm or less) using X-rays, soft X-rays, or an electron beam as an exposure light source, it has become an important task to simultaneously provide a performance capable of inhibiting occurrence of scum and bridging, in addition to providing a favorable resist performance such as having a high resolution and good roughness characteristics. There is a need in the art for solving these desired requirements.